Simulations Of Direct Impingement Nozzle Atomization Based On MPS Method

Atomizing refers to the physical phenomenas that jet or liquid sheet breaking into liquid droplets. It is one of fundamental problems of many natural phenomena and engineering applications, for example the jet atomization in high-speed airflow environment. It involves a lot of fields such as aerodynamics, multiphase flow, turbulence, heat and mass transfer and so on. As there are few tools available to investigate the detailed atomization field, its mechanism has not yet been completely understood till now. Due to its complex physical nature, it is difficult for theoretical analyses to be performed in the atomization related engineering problems. Currently, lots of efforts highly depend on experimental approaches. However, It is well-known that experimental investigations are restricted by the equipments and are expensive as well. At present, the popular commercial computational mechanics software implements multiphase numerical simulation methods. Correspondingly, the accuracy of the simulations greatly dependent on the atomization models. As a result, it is hard to use them to further and deeply understand the atomization mechanism.This paper developed a program based on Moving Particle Semi-implicit method (MPS) method. A new surface tension model and a new free surface treatment method were used. The program was used for the simulations of direct impingement nozzle atomization, and obtained agreement simulation results compared with experimental observations. The influence of surface tension and the number of particles on the simulation results were analyzed to find out their effects on the numerical accuracy. The simulation and experimental results under different flow parameters were also compared in the present study.The results show that the surface tension model and particle number have a great influence on the simulation results. By comparing the experimental results with the simulation results under different flow parameters, it can be found out that the present code can successfully simulate the different atomization modes and capture multi-scale structures of the atomization such as liquid column, the liquid film, the liquid silk, and the droplet. Therefore, the present developed code based on the MPS method has been validated to be suitable for the simulation of direct impingement nozzle in the liquid-fuel rocket.Due to the heavy computation loads of the MPS method, In this paper, efforts have been carried out on parallelization of the serial program. The large amount of computation in particle method is largely caused by the neighborhood particle search and the solving of linear equations. The parallelism of neighborhood particle search part have been implemented on the platform of CUD A. The numerical tests show that it has achieved good speed-up ratios.